REN and Parkinson disease: Meanwhile, the KEGG analysis showed that these DEGs were enriched in oxidative phosphorylation, retrograde endocannabinoid signaling, thermogenesis, Parkinson disease, ribosome, protein digestion and absorption, renin-angiotensin system, calcium signaling pathway, phenylalanine metabolism, glycosphingolipid biosynthesis-ganglio series, and propanoate metabolism.